1. Technical Field
The present invention relates to an image data processor, and more particularly, to an image data processor for processing image data input having gray scale information.
2. Related Art
Image reproducing apparatuses include cathode ray tubes (CRTs), liquid crystal displays (LCDs), ink jet printers, laser printers, photocopiers and other devices. Such image reproducing devices receive image data obtained by photographing an object or scanning an object using a scanner, and reproduce the received image data on a recording paper or a screen.
I have found that there is a need to provide an improved image data processor for efficiently and conveniently processing data.
It is an object of the present invention to provide an improved image data processor to more efficiently and conveniently process data.
It is a further object of the present invention to provide an image data processor for processing received image data into data suitable for an image reproducing apparatus, so that the resolution and gradation of a reproduced image is not greatly degraded.
Accordingly, to achieve the above objects and others, the present invention provides an image data processor for processing image data input with gray scale information corresponding to pixels in response to the number of divided-per-pixel gray scale levels that can be expressed by an image reproducing apparatus and for outputting the processed image data to the image reproducing apparatus, the processor including: a quantization portion for dividing gray scale values corresponding to the pixels of input image data by a comparison reference value set to about a gray scale between gray scale levels in which the image reproducing apparatus can express a pixel, and separately outputting the quotients and remainders of the division; a dithering portion for comparing the element values in a set dithering matrix with the remainder values at corresponding comparison positions and outputting the results of the comparison as binary bits; and a mixer for adding the quotients output by the quantization portion to the binary bits output by the dithering portion and outputting the sum to the image reproducing apparatus.
Preferably, a quotient obtained by dividing a maximum gray scale value in which the image data is expressed, by a value obtained by subtracting one from the number of gray scale levels in which the image reproducing apparatus can express for each pixel, can be set as the comparison reference value of the quantization portion. Also, it is preferable that the element values in the dithering matrix are set to gradually increase in the direction from the center to the periphery of the matrix.
The image data processor further includes a gamma compensating portion installed before the quantization portion for compensating for the gray scale values of the image data in accordance with the gradation reproduction characteristics of the image reproducing apparatus in order to compensate for the difference generated between a recording concentration reproduced by the image reproducing apparatus and a recording concentration corresponding to the gray scale value when the gray scale value of the image data is input to the quantization portion without change.